1. Field of the Invention
The present invention relates generally to contact assemblies and, more particularly, to a clamp-jaw contact assembly, such as for a watt-hour meter socket. The invention also relates to meter sockets employing clamp-jaw contact assemblies.
2. Background Information
Watt-hour meters are typically used by electric utilities to measure electrical consumption in residential, commercial and industrial applications. To accommodate the watt-hour meter, equipment is provided with a watt-hour meter socket. Such a meter socket contains a plurality of “meter jaws” to accept bayonet stabs or contacts on the base of the watt-hour meter.
Meter sockets having locking jaws for receiving the bayonet or blade contacts of a watt-hour meter are well known. See, for example, U.S. Pat. No. 3,281,550. Meter sockets are generally located in a rectangular enclosure having an opening in a top panel for receiving line cables and an opening in a bottom panel for receiving load cables. The meter socket is mounted to a back panel of the enclosure. A removable front panel has an opening for receiving the dome portion of the meter, which extends therethrough when coupled to the meter socket.
A typical residential meter socket is of the “plug-in type” in which the bayonet stabs on the meter are retained and clamped to corresponding meter jaws using the inherent spring pressure of the meter jaws. For some residential applications, and for the majority of commercial and industrial applications, a “clamp-jaw” type of meter socket is employed. In the clamp-jaw type meter socket, the clamping force of the jaws upon the meter bayonets is enhanced by the addition of a spring, such as a straight beam spring or a coil spring.
In a typical construction, the meter jaw assembly includes a stationary jaw or contact, and a moveable or pivoting jaw or contact. The moveable jaw, with the aid of the aforementioned spring, exerts pressure on the corresponding meter bayonet, thereby clamping it to the stationary jaw. The meter jaw assembly typically further includes a meter bypass which permits changing or testing of the meter without interrupting service to the load end of the meter. See, for example, U.S. Pat. No. 5,775,942. Generally, in the bypass mode of operation, the jaws of the meter jaw assemblies are opened, releasing the meter bayonets, and the line and load contacts of the same phase are shorted by an associated bypass contact member.
FIG. 1 shows a prior clamp-jaw assembly 2, which generally includes three component parts: a stationary contact 4, a moveable contact 6 and a conductor terminal (not shown). The stationary contact 4 is preferably a one-piece construction including an elongated body 8 and a generally unshaped bottom portion 10 having a vertical extension member 12 and a conductor terminal interface 13. The elongated body 8 includes a pair of wings 14, which extend perpendicular to the elongated body 8. Preferably, the stationary contact 4 is stamped and bent into shape from a single piece of conductive metal, such as copper. The moveable contact 6 is pivotally mounted to the stationary contact 4 by a pivot pin 16. The moveable contact 6 is also preferably a one-piece construction. The moveable contact 6 includes a back portion 18 having a pair of wings 20 (only one of the wings 20 is shown) extending substantially perpendicular to the back portion 18. A low portion 22 (shown in hidden line drawing) of the moveable contact 6 is bent for receiving a biasing mechanism, such as a spring 24, to bias a portion 26 of the moveable contact 6 to be in a clamped position with respect to the elongated body 8 of the stationary contact 4.
Another disadvantage of known jaw-type contact assemblies is the fact that they permit the meter bayonet or meter clip to be arbitrarily inserted between the stationary and moveable contacts, even when it would be undesirable or disadvantageous to do so (e.g., without limitation, when the watt-hour meter is not in bypass mode). Specifically, as shown in FIG. 1, the angled design of the upper portion of moveable contact 6 creates a gap 28 between moveable contact 6 and the body 8 of stationary contact 4. Therefore, the meter bayonet (not shown) potentially may be inserted into the gap 28 and the spring bias of the moveable contact 6 can potentially be overcome at any time.
There is, therefore, room for improvement in clamp-jaw contact assemblies.
There is also room for improvement in meter socket assemblies and in meter socket clamp-jaw contact assemblies.